Automatic circuit interrupter



J. H. PROCTER AUTOMATIC CIRCUIT INTEBRUPTER' Original Filed April 23. 1920 June 21 1927.

T A W I WITNESSES: i INVENTOR 11/ 7. [0 J5pb// P0 BY I I ATTORNEY Patented June 21, 1927.

UNITED STATES PATENT OFFICE.

osiarn n. rnocrnn, or. PITTSBURGH,

PENNSYLVANIA, ASSIGNOR TO WESTING- VANIA.

nu'romr'xd cmcurr INTEBBUPTER.

Application filed April 23, 1920, Serial No. 875,965. Renewed April 27, 1927. w

' My invention relates to automatic circuitinterrupters and particularly to selective reclosing circuit-interrupter-s.

One object. of my invention is to provide a circuit-interrupter that shall aut'omatically completely disconnect the circuit upon the occurrence of an overload or a shortcircuit and that shall reconnect the circuit automatically when the overload or shortcircuit is removed.

Another object of my invention is to provide means for controlling the reclosing. of, the interrupter that shall be simple andcompact in construction and accurate and reliable in operation.

The occurrence of a heavy overload or short-circuit upon feeder-circuit conductors causes a current to traverse the conductors that exceeds in value the normal carrying capacity of the circuit. Upon the occurrence of such conditions, it is desirable to open a circuit interrupter to prevent the.

traversal of current until the heavy overload or short-circuit conditions are removed. Since the opening of the interrupter may be 'efiected automatically upon the occurrence of such conditions, itis highly desirable that the reclosing of the interrupter may also be automatically effected when these conditions are removed. Either a large in I crease in the load on a circuit or a short circuit thereon will materially decrease the resistance of'the circuit comprising the load 7 and the feeder conductors. Conversely, a decrease in the load on-the circuit or the removal of'a-short-circuit therefrom will increase the resistance of the circuit. By"

measuring the resistance of the circuit so formedand by making the reclosing of the interrupter dependent upon the resistance of the circuit attaining a predetermined value, the interrupter may be automatically and selectively 'reclosed. Inasmuch asthe interrupter will not be reclosed until a predetermined resistance obtains in the circuit,

' all. danger from excessive currents is obthe opening of the interrupter, a resistancemeasuring means comprising a Wheatstone bridge is so connected to the feeder-circuit conductors that the load or the short-circuit thereon com rises the fourth arm of the Wheatstone bridge. Instead of the ordinary g'alvanometer, a control coil is provid- ,ed that is adapted, when suificiently energized, to render the closing means operative again, By employing resistors of predeter: mined values for the other three arms of the Wheatstone bridge, the control coil may be arranged to operate at a predetermined minimum current and may be made adjustable for currents of larger values. Since the value of this current is dependent upon the resistance of the circuit throughthe overload or short-circuit, the control coil may be arranged to operate when the resistance of the feeder'circuit attains a predetermined value. With this arrangement, the defective circuit may be completely isolated until such time as its fault is removed.

In the accompanying drawings,-Figure 1 is a diagrammatic view of a direct-current circuit embodying my invention; Fig. 2 is a diagrammatic view of an alternating-cur- Fig. 3 is a diagrammatic view of the tripping and resetting means used in connection with the circuit-interrupter. 1

A circuit 1 receives energy through a cirexit-interrupter 2 from a plurality of busbar conductors 3 that are energized from a direct-current source of electromotive force closing coil 5 that may be directly energized irom the bus-bars 3 through a switch 6 and an auxiliary switch 7. The auxiliary switch 7 is actuated, through a trip magnet 8, to open the circuit ofthe closing winding 5 when an excessive current traverses the interrupter 2. Upon the actuationof the auxiliary switch 7, a latching member 9 is adpated to so engage a cam 10, that 'is mounted on the operating rod 11 of the auxiliary switch 7, as to maintain the auxiliary switch 7 in its open position. When rent circuit embodying my. invention,'and.

4. The interrupter 2 is provided with a .the interrupter2 is open engagement is severally efiected, by means of a plurality of interlocking switches, between contact members 12, 13 and 14;, respectively. A dash of the circuit 1 are so connected, through the contact members 12 and 13 of the interrupter 2, as to form the fourth arm .of the bridge 16. A control coil 20 is employed instead of the usual galvanometer and serves, when sufficiently energized, to reset the auxiliary switch 7 by so actuating the latch member 9 as to release the cam member 10. A resistor 21 is connected, in series with the Wheatstone'b'ridge 16, across the bus-bar conductors 3 and is employed merely to limit the value of current that may traverse the bridge 16. 1

In Fig. 2 is illustrated the manner of applying the reclosing control system to an alternating current circuit. A source 22 of alternating current supplies energy to the feeder circuit 1 through the interrupter 2. The interrupter is provided with the closing coil 5, the circuit of which is controlled by a manually-operable switch 6 and an auxiliary switch 7. Energy for maintaining the coil 5 energized is derived from a source 23 of energy while conditions are normal.

When an overload or short-circuit occurs on the circuit 1, the auxiliary switch 7 is opened by the overload trip magnet 8 and is maintained in its open position by the latching member 9, as previously described in connection with the system that is illustrated in Fig. 1. Upon the opening of the switch 7, the circuit interrupter 2 opens, thereby closing the switches 12, 13 and 14 to connect the Wheatstone bridge 16 to the conductors of the circuit 1 and to the source 23. When the short-circuit conditions on the circuit 1 are removed and the resistance of the load connected to the circuit increases to a predetermined value, the control coil 20 actuates the latching member 9 to ermit the resetting of the auxiliary switch and the interrupter 2 is immediately reclosed.

The diagrammatic view illustrated in Fig. 3 shows the action of the latching member 9 when the auxiliary switch 7 is in its open position. The energization of the coil 20 so actuates the latching member 9 as to release the cam member 10 and thereupon permit the auxiliary switch 7 to reset itself.

When it is desired to close the interrupter 2, the switch 6 is closed to permit the energization .of the closing coil 5 of the interrupter 2. Upon the occurrence of a heavy overload or short-circuit at the point A in the circuit 1, an excessive current is causedto traverse the tripping magnet 8, whereupon the auxiliary switch 7 is opened. The latching member 9 immediately engages the cam member 10 and maintains the auxiliary switch 7 in its open position. Upon the opening of the interrupter 2, the Wheatstone bridge 16 is connected to the circuit 1 and to its source of energy 3.. So long as the resistance at the point A remains below a predetermined value, the control coil 20 is not sufficiently energized to so actuate the latching member 9 as to reset the auxiliary switch 7. When the resistance of the overload or of the short-circuit increases, however, to a predetermined value, the bridge 16 becomes unbalanced, and the control coil 20 becomes sufficiently energized to actuate the latching member 9. The auxiliary switch 7 immediately resets itself and reestablishes the circuit of the closing winding 5, and the interrupter 2 is reclosed. By means of the sensitive Wheatstone bridge arrangement, the reclosing of the interrupter is made selective and dependent upon predetermined conditions in the circuit 1.

Although I have shown a diagrammatic view of a circuit embodying my invention, I do not limit my invention to the structures and arrangements illustrated, as various modifications may be made therein without departing from the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention:

1. In an electrical distributing system, the combination with an interrupter, of means for opening the interrupter to completely disconnect both sides of a circuit and means thereafter connected to the circuit conductors and rendered operative to preclude the relosing of the interrupter until the load conditions on the circuit so change as to preclude current from traversing the interrupter in excess of a predetermined value, said means constituting, with the circuit conductors, a Wheatstone bridge.

2. In an electrical distributing system, the combination with a supply circuit and a feeder circuit, of an interrupter between said circuits for disconnecting both sides of the circuits, means for tripping the interrupter upon the occurrence of a short-circuit in the feeder circuit to completely disconnect the supply and the feeder circuits, and means thereafter rendered operative to reclose the interrupter when the resistance of the short-circuit increases to a predetermined value, said means comprising a Wheatstone bridge;

3. In an electrical distributing system, the combination with a supply circuit and a feeder circuit, of an interrupter between said circuits for disconnecting both sides of the circuits, means for tripping the interrupter upon the occurrence of a shortcircuit in the feeder circuit to completely "disconnect the two circuits, and means thereupon rendered operative to preclude the reclosing of the interru ter untilthe shortcircuit conditions are e iminated, saidmeans constituting a network of resistors, the potential between predetermined points of which as controlled by the short-circuit conditions.

.rupter comprising a Wheatstone brid combination with a supply circuit, a feeder circuit, and an interrupter between said circuits, of means for tripping the interrupter upon the occurrence of a short-circuit in the feeder circuit, means for reclosing the interof which the short-circuit on the feeder circuit comprises the fourth arm' and means for energizing the bridge.

6. In an electrical distributing system, the combination with a supply circuit, a feeder circuit, and an interrupter between said circuits, of means for tripping the interrupterupon the occurrence of ashort-circuit in the feeder circuit, means forreclosing the inter rupter comprising a Wheatstone bridge the unbalancing of which is responsive to the variation in the short-circuit .conditions. i

.7. In an electricaldistributing system, the combination with a supply circuit, a feeder circuit, and an interrupter between said circuits, of means for trip ing'the interrupter upon the'occurrence o a short-circuit in the feeder circuit, means for reclosing the interrupter comprising a Wheatstone bridge ofwhich the short-circuit on the feeder circuit comprises the fourth arm, means for energizing the bridge and means for disconnecting the reclosing means when the\inter-- rupter is closed.

8. In an electrical distributing system, the combination with a supply circuit, a feeder circuit, and an interrupter between saidycircuits, of means for tripping the interrupter upon the occurrence of a short-circuit in the feeder circuit, means for reclosing the interrupter comprising a \Vheatstone bridge of which the short-circuit on the feeder circuit comprises the fourth arm, means for eners gizing the bridge and means for de-energizing the Wheatstone bridge when the interru erisclosed.

9. n an electrical distributing system, the combination with a supply circuit and a feeder circuit, of an interrupter for completely disconnecting both sides of said circuits means for tripping the interrupter uphe occurrence of a short-circuit in the feeder circuit, a Wheatstone-bridge resistance-measuring means energized from the supply circuit for reclosing'the interrupter when the resistance of the short-circuit changes to a predetermined-value and means for rendering the measuring means inoperative when the interrupter is closed.

10. In an electrical distributing system, the combination with a supply circuit, a feeder circuit and an interrupter between said circuits, of means for tripping theinterrupter. upon the occurrence of a short-circuit in the feeder circuit, means for reclosing the interrupter comprising a Wheatstone bridge of which the short-circuit on the feedercircuit comprises the'fourth arm,-means for energizing the bridge, means controlledby the interrupter for connectingv the feeder circuit to the bridge and means for disconnecting the feeder circuit from the bridge under predetermined conditions.

11. In an electrical distributing system, the combinationwith a s'upplycircuit and a feeder circuit, of an interrupter for com pletely disconnecting both sides of said circuits, means for opening the interrupter when a heavy overload occurs on the feeder circuit and means comprising a resistance measuring network energized from the supply circuit for reclosing the interrupter when load conditions so change as to re vent current in excess of a predetermined value from traversing the interrupter.

12. In an electrical distributing system, the combination with a supply circuit and a feeder, circuit, of an interrupter for completely disconnecting both sides of said circuits, means for: opening the interrupter when a heavy overload occurs on the feeder circuit, means for reclosing the interrupter, P

and a resistance-measuring means com rising a network of resistors energized rom the supply circuit for controlling the reclosing means.

13; In an electrical distributing system,.

the combination with a supply circuit and 115 a feeder circuit, of an interrup'ter for completely disconnecting both sides of said one cuits, means for opening the interrupter "when a heavy overload occurs on the feeder circuit, means for reciosing the interrupter, and meanscomprising a resistance-measuring network energized from the supply circurt to energize the reclosing means when i the resistance of the load-circuit changes to 5 a predetermined value.

14:. In an electrical distributing system, the combination with a supply circuit, a feeder circuit and an interrupter between said circuits, of means for opening the inter'rupter when a heavy overload occurs on the feeder circuit, means for reclosing the interrupter and a Wheatstone bridge for controlling the reclosing means.

15. The combination with two circuit sections and a circuit interrupter therebetween, of a plurality of resistors and means operative after the opening of the inter- 4 rupter for connecting the resistors to the circuit sections to constitute a Wheatstone bridge, one arm .of which shall comprise one circuit section and the load connected thereto.

16. A control circuit for an interrupter, said circuit being constituted by an electromagnet connected across one diagonal of a Wheatstone bridge having one arm constituted by the circuit controlled by said interrupter, and having a source of electromotive force connected across its other diagonal. v

In testimony whereof, I have hereunto subscribed my name this 13th day of April,

JOSEPH H. PROCTER 

